Kara was born on Picon, but she was raised all over the twelve colonies. The daughter of a career enlisted woman, her childhood was spent bouncing from one military outpost to another. Kara's father, Dreilide, was a frustrated musician, forever trying to write songs and make it into the big time and forever failing to make his mark. Her mother, Socrata, was a Sergeant Major in the Colonial Marines, attached to an artillery company and a decorated veteran of the Cylon War.

Kara was a tough and tough-minded child, more interested in sports than in the military, she dreamed of playing Pyramid in the big leagues someday. At every base, there was a Pyramid court and Kara was a born athlete, able to both slice and duck around opponents on her way to planting the slippery ball into the goal or to block and tackle the opposing players on defense. Her mother had won the Star of Valor in the Cylon War and this honor entitled her daughter to a place at the Fleet Academy if she wanted it. At first, Kara wasn't interested and wanted to pursue a college scholarship, but her school records were spotty at best. Finally realizing that the Academy had one of the best Pyramid teams at the collegiate level, Kara decided to enter the Academy, serve her three years required enlistment and then resign and pursue a professional Pyramid career.

Kara played Pyramid well at the Academy, and was being actively scouted by the major league teams when a vicious hit shattered her right knee during a playoff game in her sophomore year. Even after months of reconstructive surgeries and physical therapy, it was clear that the leg would never be the same. Kara would have to look for a different career.

Depressed, she applied to all the various post-graduate training schools, but doubted she'd be accepted to any of them with her academic record. But to her shock, she scored higher on the flight training entrance exam than anyone in the history of the program and she was accepted into the next class.

Kara was what the instructors called a true stick and rudder woman; someone who flew by instinct not instruction. To her own surprise, Kara found herself in love with flying. She'd never thought that anything could equal the feeling she had on the Pyramid court, but flying actually surpassed it. She found a freedom in the air she'd never experienced before, a joy and effortlessness that was new and welcome into her hardscrabble life. All thoughts of leaving the service after three years were gone. She would be a pilot for the rest of her life - that is, unless she was kicked out of the Fleet.

Kara hated taking orders. Hated military protocol. Hated the rules and regulations that were part and parcel of the military life. Her record at the Academy and then at flight school was littered with demerits, reprimands, and negative evaluations by her superiors. She drank too much, gambled too much, broke curfew almost daily, somehow always managed to be involved in any bar fight at the local watering holes and had a reputation for leaving a string of men with broken hearts and broken backs after sexual encounters that were more akin to a game of tackle Pyramid than lovemaking. Simply put, she was a disaster as a military officer. But no one could argue with her flying. While her academic and personal record kept her from graduating first in her class, she set new records on almost every hands-on flying test she encountered. Clearly, she was destined to fly Vipers and just as clearly she would be a handful for any squadron leader unfortunate to have her under their command.

Kara served her first tour aboard the battlestar Triton and while she was loved and admired by the other pilots, she was reviled by the ship's commander, who wanted her off the Triton as soon as possible. What to do with her became a problem, since no other ship would take her. Fortunately, a slot opened up as an instructor at flight school and Kara was immediately shipped right back where she started.

It was there that Kara met Zak Adama and fell in love for the first time in her life. There'd never been a lack of men in her life, but she'd never seriously considered the possibility of a long-term relationship. Zak was different. Something about him touched and moved Kara, made her want to break all the rules of the heart she'd lived by all her life.

When she met Zak's brother Lee, she briefly thought she'd made a profound mistake. While Zak touched her maternal instincts, made her want to protect and nurture the shy, young pilot, his brother touched her in a deeper and more womanly way. Lee Adama's entire carriage and attitude was a challenge to Kara Thrace, and Kara Thrace had never walked away from a challenge. But then the weekend passed, and Lee left to rejoin his squadron, and Kara firmly put aside the feelings as the momentary wandering of a rogue's heart.

Then Zak failed a key flight test. A test Kara was administering. Zak was on the bubble as far as flight school was concerned and failing this test was a sure ticket out. It was Kara's duty to fail him. But she couldn't do it, couldn't destroy Zak's dream of becoming a pilot like his father. She passed him and made a promise to herself that she would teach Zak everything he needed to know and make sure he became a great pilot.

It wasn't enough. The board of inquiry determined that Zak Adama's plane had crashed due to "pilot error." Kara was devastated, bereft, ready to resign her commission right after Zak's funeral. But that day, Zak's father sought out Kara and asked the woman who was almost his daughter-in-law to stand with the family at the gravesite. She stood next to Commander Adama in the bright sunshine of the Caprican morning and felt his arm go around her when tears began to stream down her cheeks and a bond was formed between them. Adama asked her to join him as a pilot aboard the Galactica and Kara readily agreed. She spent the next two years aboard Galactica, for the most part managing to stay out of the brig and concentrating on just flying. Adama kept an eye on her and the two of them became more like father and daughter than pilot and commander.

"Remember, we're all flying solo on this mission. So that means there'll be nobody there to bitch slap you if you start to get tired or start seeing little toasters on your wing."

—Kara briefing the pilots.

Kara thinks with her nerve endings. She not only wears her heart on her sleeve, she'll throw it at you if you're not paying attention. A rule-breaker by nature and a hell-raiser by preference, she nevertheless not only respects, but reveres the traditions and customs of the military service. Few things are guaranteed to bring a tear to her eye more than hearing the Colonial anthem and watching the flag go up the halyard.

She is proud of her uniform, proud of her place in the long tradition of pilots who've gone before, and is politically conservative to the point of being almost reactionary. She's also loyal to a fault, and fiercely protective of her friends and family.